Dynamic optical coherence tomography for paper wetting measurements

摘要

This paper introduces a novel optical method to measure liquid penetration into porous, highly scattering media. Testing was conducted by measuring the sorption of glycerol into a paper sample consisting of cellulose fibre tissue with a grammage of 115 g m~(-2). During wetting, optical coherence tomography (OCT) was used to detect dynamical changes in the sample's scattering properties. Distinguishing the border between the dry and the wetted area on the basis of separate A-scans was a challenging task. However, wetting behaviour could be investigated in the depth direction simply by constructing a composite image of the separate scans. In addition, the method also allowed the imaging of swelling behaviour in paper.